A shuttlecock equipped with a cap and a skirt part adjacent to the cap is widely used in badminton. An air passage hole is formed to the skirt part of the shuttlecock, and an air flow directed to the skirt part passes through the air passage hole when the shuttlecock flies in the air.
On the other hand, when the shuttlecock is struck by a racket in a badminton game, the skirt part collapses by such strike (for example, refer to PTL 1).
Citation List
Patent Literature
PTL 1 Japanese Patent No. 3181059